The present invention relates to an endoscope system that is capable of capturing in vivo OCT (Optical Coherence Tomography) images of an object.
Conventionally, endoscopic devices for observing objects inside a human cavity have been known. Such an endoscope is provided with an endoscope to be inserted inside the human cavity, and an illuminative external device, which is to be connected to the endoscope. The external device includes a light source unit for illuminating the object and a processor for processing image signals.
The endoscope includes:
an illuminating optical system, which is connected to the light source unit of the external device and used for illuminating an object (e.g., the paries of a body cavity);
an objective optical system for forming an optical image of the object; and
a CCD (Charge Coupled Device) provided substantially at a focal plane of the objective optical system and electrically connected to the processor of the external device.
At a tip end of the endoscope, an instrument opening is formed. Forceps or various kinds of treatment instruments inserted in the endoscope are protruded from the instrument opening inside the human cavity.
With the endoscope system described above, an operator is capable of observing inside the human cavity. The operator firstly inserts the endoscope inside the human cavity. Light emitted by the light source unit of the external device is projected to an object to be observed through the illuminating optical system. An optical image of the illuminated object is formed, through the objective optical system, on the light receiving surface of the CCD. The CCD converts the received optical image into an electronic image (i.e., image signal), which is transmitted to the processor of the external device. The processor processes the received image signal, and display the image of the object on a displaying device. Thus, the operator is capable of observing inside the human cavity of a patient through the displaying device.
If the operator judged that there is a possibility of a cancer or a tumor with in the observing portion of the human cavity, a forceps or biopsy instrument is inserted in an instrument channel inside the endoscope. The tip portion of the instrument is protruded from the instrument opening, and the tissues of the portion in question can be collected. The tissues thus obtained is subjected to a pathological inspection, and based on the results of the inspection, diagnosis is made.
According to the conventional endoscope system as described above, only the surface of the human cavity is observable. In order to know the condition of tissues beneath the paries of the human cavity, biopsy operation is required. In particular, in order to find an early cancer or a small tumor, the biopsy operation is indispensable. However, the pathological inspection requires time, and therefore, the diagnosis requires time.
Further, in view of a burden to the patient, the biopsy can be done only in a limited area and by a limited number of times. Diseased portion may be present at a portion other than the portion identified by the operator. However, such a portion might be overlooked, and as a result, an accurate diagnosis may not be done even if the pathological inspection is performed.
It is therefore an object of the present invention to provide an improved endoscope system which enables an accurate diagnosis within a relatively short period of time.
For the object, according to the present invention, there is provided an endoscope system, which is provided with a first light guide, a second light guide, an optical coupler for optically coupling the first and second light guides, a low-coherent light source that emits a low-coherent light beam, the low-coherent light source being provided at a proximal end side of one of the first and second light guides, the light emitted by the low-coherent light source being incident on the one of the first and second light guides, a scanning unit that causes the light beam emerged from the first light guide to scan on a predetermined surface of the object, the scanning unit directing the light beam reflected by the object to the first light guide as a detection light beam, a reflector that reflects a light beam emerged from the second light guide to the second light guide as a reference beam, an optical path length adjusting system that relatively changes a length of an optical path length from the optical coupler to the object via the first light guide and an optical path length from the optical coupler to the reflector via the second light guide, a light detecting device provided at a proximal end side of the other of the first and second light guides, the light detecting device detecting an interfered beam generated due to interference between the reference beam and the detection beam, and a signal processing system that generates a tomogram based on the signal detected by the light detecting device when the optical path length adjusting system and the scanning unit operate.
Optionally, the first light guide includes a plurality of optical paths, the second light guide includes a plurality of optical paths, the number of the optical paths included in the second light guide being equal to the number of the optical path included in the first light guide, the optical coupler couples the plurality of optical paths included in the first light guide with the plurality of optical paths included in the second light guide, respectively. The scanning unit causes the light beams emitted from the plurality of optical paths of the first light guide to be incident on the object with the plurality of light beams being aligned such that a detection line is formed on the object, the scanning unit shifting the detection line in a direction perpendicular to the detection line so as to scan a predetermined two-dimensional area, the plurality of beams reflected by the object being directed to the plurality of optical paths of the first light guide via the scanning unit.
In another case, each of the first and second light guides is composed of a fiber array having a plurality of single-mode optical fibers arranged in parallel.
Optionally, the scanning unit includes a deflector that deflects the plurality of light beams emitted from the tip of the plurality of optical paths of the first light guide toward the object with the plurality of beams aligned in parallel, and shifts the detection line in the direction perpendicular to the detection line with the plurality of beams remained to be aligned in parallel.
In a particular case, each of the first and second light guides includes a single optical path, and wherein the scanning device includes a main scanning device which shifts the incident position of the beam, on the object, emitted by the first light guide in a main scanning direction, and an auxiliary scanning device which shifts the incident position of the beam, on the object, emitted by the first light guide in an auxiliary scanning direction which is perpendicular to the main scanning direction.
Optionally, the signal processing system generates a tomogram of the object, the tomogram corresponding to an area from a surface of the object to a predetermined depth therefrom.
Still optionally, the optical path length adjusting system moves the reflector toward/away from a tip of the second light guide to vary the optical path length from the optical coupler to the reflector via the second light guide relative to the optical path length from the optical coupler to the object via the first light guide.
Preferably, the low-coherent light source includes a super-luminous diode.
Further optionally, the endoscope system may further be provided with an illuminating optical system that emits visible light and/or excitation light which causes biotissues to fluoresce, to the object, an objective optical system that converges the light from the surface of the object to form an object image, and an image capturing system that captures the optical image formed by the objective optical system.
Furthermore, the endoscope system may be provided with a visible light source emitting visible light, an excitation light source emitting the excitation light, a light source switching system that selects one of the visible light and the excitation light and causes the selected one of the visible light and excitation light to be incident on the illuminating optical system. The objective optical system forms a normal light image of the object when the visible light is incident in the illuminating optical system, and the objective optical system forms a fluorescent light image of the object when the excitation light is incident in the illuminating optical system.
Still optionally, the endoscope system may be provided with a displaying device that displays the object image captured by the image capturing system, and the tomogram generated by the signal processing system.